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| | Emission of greenhouse gases causes global warming:
Coal electrical stations, automobile exhausts, industrial pipes and
other contaminating sources, created by man, cumulatively emit
approximately 22 billion tones of carbon dioxide and other greenhouse
gases into atmosphere every year. Animal husbandry, usage of
fertilizers, burning of coal and other sources generate approximately
250 million tones of methane per year. Over 50% of all greenhouse
gases, generated by mankind, remain in atmosphere. From pre-industrial
period in the middle of 18th century, concentrations of carbon
dioxide and methane increased by 34% (up to 0.039% as per volume) and
160% respectively. These values are very high for the last 420 000
years - period, for which reliable data, obtained from Earth's
glaciers, is available. For the last 20 years, over ¾ of entire
anthropologic emissions of greenhouse gases are due to the usage of
oil, natural gas and coal. Most of the rest is due to land-use change,
in particular deforestation.
The following facts argue in favor of specified theory: Global warming,
observed during winters would be more significant than in summers and
significant in nights than during day time, in high latitudes than in
middle and low latitudes; quick heating of troposphere layers take
place against the background of not so quick cooling of stratosphere
layers.
Other theories:
Solar variation
Hypotheses have been proposed that variations in solar output may have
contributed to recent global warming.
In third assessment of IPCC, it is claimed that the solar and volcanic
activities could explain halve of temperature variations till 1950 but
after this, their cumulative effect is approximately zero. In
particular, influence of greenhouse effect from 1750, according to the
assessment of IPCC, is 8 times more than the influence of variation in
solar activity.
More recent works confirmed the effects of solar variation on global warming
post 1950. Nevertheless, conclusions were almost identical: "Best
assessment for the contribution of solar activity towards global warming fall
within the limits, ranging from 16% to 36% contribution of greenhouse
effect" ("Do Models Underestimate the Solar Contribution to Recent
Climate Change?" Petter A, Scott, Gereth & John R. Gyakum, "Journal of
Climate", December 15, 2003).
Series of works, which propose existence of mechanisms, amplifying the
effect of solar activity do exist. These works are not considered in
modern models or that the importance of solar activity in comparison
with other factors is underestimated. Such assertions are disputed, but are active concepts for study.
Conclusions, which would be outcome of this discussion, can play key
role in determining the degree of accountability of mankind for the
climate variation and also of the natural factors.
Other theories:
Several other hypotheses exist:
The observed global warming is within the limits of natural variability of
climate and separate debate is not required.
Global warming appeared as a result of exit from cold Little Ice Age.
Global warming is observed for insignificant period and hence, it is very
difficult to confidently say that the global warming is taking place at all
or not.
It is important to note that the climate on Earth changes periodically
based on the recurring processes, occurring in the system of
Earth Sun outer space. According to recent classification, four cycle
groups are conventionally allocated. Extra-duration of over 150-300
million years are related to most significant changes in ecological
conditions on Earth. They are related to rhythms of tectonics and
volcanism. Lengthy cycles are also related to rhythms of volcanic
activities and stretching over tens of million years. Short - hundreds
and thousands of years - stipulated by variations in parameters of
Earth's orbit. Last category is conventionally called "Ultras-short.
They are related to rhythms of Sun. Cycle 2400 years, 200, 90, 11 years
are present amongst them. Without exception, particularly the
specified rhythms are determining factors in global warming, observed on the
planet. Still, man is not in a position to neither modify nor
influence upon these processes. Currently, not even one of these
alternative theories has significant number of supporters amongst the
scientists - climatologists. |
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Scientists from around the world gathered Monday in Paris at 
